It seems feasible if you don’t imagine they’re all big novels. A lot of nonfiction you might borrow several of in one visit and not read front to back. Think recipe books, handicrafts, anything along those lines. Could also be smaller things like children’s books, poetry collections, etc., or some of the books were unusually expensive.

I spent a few months in Germany years ago, and “Americans” (Amerikaner) tended to be used to refer to people from the Americas (either NA specifically or NA and SA collectively) in my experience. If you wanted to say someone was from the US, you’d say something more like “aus den USA.”